The present invention relates to a drilling mast for a drilling vessel, for drilling in the ground, for example for oil or gas, by means of the drilling mast, which drilling mast at the top side is provided with first hoisting means in a first firing line, for manipulating a first object, such as a drill string, in the longitudinal direction of the mast, and with second hoisting means in a second firing line, for manipulating the position of a second object, such as a second drill string, in the longitudinal direction of the mast.
It is known in the prior art to drill from a drilling vessel, for example for oil or gas. A drilling vessel that is used for this application is known from British Patent Application GB 2291664 A.
Drilling from such a vessel is carried out with a drilling tool fixed on the end of a drill string. The drill string is composed of loose drill string elements. The drill string elements consist mainly of a piece of pipe, which is provided on either side with fixing elements for connecting together adjacent pipes.
During the drilling, the drilling tool is guided in the direction of the seabed by means of the drill string. A new drill string element is constantly added to the drill string at the top, so that the drilling tool can extend ever further in the direction of the seabed. Assembling such a drill string takes a relatively long time, despite the fact that the drill string can move freely through the water. Another factor is that the greater the depth to which drilling has to be carried out, the more time is needed for assembling the drill string and for moving the drilling tool in the direction of the seabed. During drilling, a drilling tool inevitably becomes blunt. That means that the drilling tool has to be replaced by a new, sharp tool. In order to be able to raise the worn tool, the drill string has to be hoisted up in its entirety. During the hoisting operation the drill string is disassembled. This hoisting up of the drill string, including drilling tool, also takes a relatively long time.
In order to prevent a great deal of time from being lost in assembling or dismantling a drill string, it is advantageous to have first and second hoisting means available next to each other for the purpose of installing below them a first and a second drill string respectively. During the disassembly of the drill string to replace the tool, it is possible to make a start on the assembly of a new drill string with a new tool on it.
U.S. Pat. No. 6,085,851 discloses a drilling tower that has below it a first and second hoisting means above a first and second firing line respectively. The first and second hoisting means can be used simultaneously. The drilling tower according to U.S. Pat. No. 6,085,851 is constructed as a lattice structure. The mast is in the shape of a narrow high pyramid with the top cut off. The hoisting means and the firing lines are inside this lattice structure, which means that the hoisting means and the firing lines are separated from the outside world by the lattice structure. The hoisting means and the firing lines are therefore difficult to reach from the outside, which is a disadvantage.
A so-called setback is used during the drilling process. This setback is a temporary storage of drill string elements on a ship. During the assembly and the dismantling of a drill string, so-called multi-joints can be set in a setback. Multi-joints are units of two or more drill string elements each, which can be held in storage in the vertical position in the setback. From the setback the drill string elements can be supplied in multi-joints to the firing line. Since the firing lines of the drilling mast according to U.S. Pat. No. 6,085,851 are difficult to reach from the outside of the mast, the setbacks have to be placed in the lattice structure. In order to use the two firing lines simultaneously, two setbacks even have to be present in the lattice structure. That is a disadvantage, for the simple reason that little space is available in the lattice structure itself.
Certainly if work is being carried out at fairly great depth, it must be possible to feed in drill string elements to the firing lines from the outside of the drilling mast. Since the firing lines are screened off by the lattice structure, complex handling tools are necessary for this purpose, which is a disadvantage.
The invention is a multiple lift hoist system for a drilling vessel made of a hollow mast connected to a drilling vessel. The mast supports the hoisting devices. The lift system contains hoisting devices located in firing lines to manipulate a drill strings in a direction longitudinal to the mast. Cables and winches located in the mast position the hoisting devices relative to the mast so the firing lines are accessible from the outside of the mast.
The invention also contemplates the same multiple lift hoist system described above for use.
The invention is a method for lifting equipment with a multiple lift hoist tower. Hoisting devices manipulate drill strings in a direction longitudinal to the mast. The cables and winches located within the hollow mast position the hoisting devices so the hoisting devices are accessible from the outside of the mast. The invention contemplated that between 2 and 6 hoisting devices can be used.
The invention is also a method for installing tubing for a well. Loose tubulars are first loaded into container then placed on a barge. The tubular support includes numerous connectors attached to each end of the container for lifting and locking containers together. The method involves moving the barge to a drilling rig, placing the containers on the drilling rig, and connecting the containers together with connectors making a container assembly. The method continues by connecting a first tubular in a first container to a second tubular in a second container for each assembly. The method ends by moving the container assemblies to the lifting positions next to the firing line, lifting the container assemblies with the connected tubulars to a vertical position, and removing individual connected tubulars from the container assembly for running into the well using the pipe racking cranes while simultaneously lowering the container assemblies for storage.